While I was at the 2009 RVIA Show this year Monaco RV LLC a Navistar Company was only showing gasoline powered motorhomes on Ford Chassis.
Reason being is that they had a number in inventory to build on. Going forward perhaps we might see more Workhorse front gas but I'm thinking the front diesel might make a go at it in the 20,500-22K weight range using a W20D OR W22D.
We still haven't read about a definite gasoline replacement engine for the 8.1L Vortec and I for one am eager to find out what direction the company will go in regards to gas powered chassis products.
I do think that the MaxxForce 7 and an Allison 6 Speed will be a good powertrain combination in the right weight motorhome.